As regulated in the Long Term Evolve (LTE) protocol, public pilot frequency symbols can be used to obtain the channel estimation value required for demodulating data. When public pilot frequency symbols can be used to obtain the channel estimation value required for demodulating data, an eNodeB determines a precoding matrix of a user equipment (UE), and notifies the UE of the precoding matrix index (PMI) corresponding to the precoding matrix. According to the public pilot frequency and PMI, the UE obtains the channel estimation value required for demodulating data. In Multiple User Multiple Input Multiple Output (MU-MIMO) working mode, the eNodeB needs to notify the UE of a power offset. The UE can learn, according to the power offset, whether matching UEs exist, and then obtains, according to the public pilot frequency, PMI and power offset, the channel estimation value required for demodulating MU-MIMO data.
In the LTE+ technology, dedicated pilot frequency symbols are used to obtain the channel estimation value required for demodulating data. In a dedicated pilot frequency channel, pilot frequency signals are combined with data signals in time division or frequency division multiplexing mode for transmission. During data transmission, the eNodeB notifies the UE of the number of transmission layers used in data transmission. At the receiving end, after receiving the receive signal, the UE obtains, according to the number of transmission layers and pilot frequency resources that are used for transmitting pilot frequency symbols and are corresponding to each transmission layer, the channel estimation value required for demodulating data, and demodulates the data according to the channel estimation value to obtain service data. The code of the pilot frequency resources corresponding to each transmission layer can be preset by the UE as notified by the eNodeB or preset with the UE.
During implementation of the present invention, the inventor finds at least the following problems in the existing technology of using dedicated pilot frequency symbols in data demodulation:
The eNodeB notifies the UE of only the number of transmission layers used for data transmission. In MU-MIMO transmission mode, multiple UEs transmit data through different transmission layers. A UE cannot determine the specific pilot frequency resources based only on the number of transmission layers used for data transmission. Therefore, multiple UEs may use the same pilot frequency resources. The specific UE channels cannot be distinguished. In this case, no accurate channel estimation values can be obtained. As a result, the channel estimation performance is lowered, and the correct service data cannot be obtained.